[简答题]Until such time as mankind has the sense to lower its population to the points where the planet can provide a comfortable support for all, people will have to accept more “unnatural food.”

[填空题]According to the author, in what sense is time like money

[简答题]

The time has come for humanity to journey to Mars. We’re ready. 46)Though Mars is distant, we are far better prepared today to send humans to Mars than we were to travel to the Moon at the commencement of the space age. Given the will, we could have our first teams on Mars within a decade. The reasons for going to Mars are powerful.
We must go for the knowledge of Mars. Our robotic probes have revealed that Mars was once a warm and wet planet, suitable for hosting life’s origin. But did it A search for fossils on the Martian surface or microbes in groundwater below could provide the answer. If found, they would show that the origin of life is not unique to the Earth, and, by implication, reveal a universe that is filled with life and probably intelligence as well. 47)From the view point of learning our true place in the universe, this would be the most important scientific enlightenment since Copernicus.
We must go for knowledge of Earth.

[简答题]Many a time has the child been told not to play with fire ____________(但是他听不进去).

[填空题]The value of spare time has become(increasing) _______ dear for most Americans.

[单项选择]Mrs. White has a hard time because she has six children（）
A. look after
B. to be looked after
C. to look after
D. looking after

[填空题]Why does the author say Newton has a unique sense of humor

[填空题]Every worker has a highly developed sense of how much work______(expect)of him.

[填空题]The X - 34 has a reusable lower stage and an expendable upper, the goal of designs is______.

[单项选择]What kind of part time job has Pat taken for the past two years
A. research engineer
B. auto mechanic
C. sales manager
D. motorbike mechanic

[填空题]The average Belgian has a lower ______ than the average Czech.

[单项选择] For some time past it has been widely accepted that babies and other creatures learn to do things because certain acts lead to "rewards" , and there is no reason to doubt that this is true. But it used also to be widely believed that effective rewards, at least in the early stages, had to be directly related to such basic physiological " drives" as thirst or hunger. In other words, a baby would learn if he got food or drink, some sort of physical comfort, not otherwise. It is now clear that this is not so. Babies will learn to behave in ways that produce results in the world with no reward except the successful outcome. Papousek began his studies by using milk in the normal way to " reward" the babies and so teach them to carry out some simple movements, such as turning the head to one side or the other. Then he noticed that a baby who had had enough to drink would refuse the milk but would still go on making the learned response with clear signs of pleasure. So he began
A. have the lights turned on
B. be rewarded with milk
C. please their parents
D. be praised